Metal box-corner fastener



'eg, 2, 1924.v

A. E. BLACKMAN METAL BOX CORNER FASTENER Filed April 23 1921 m A m Wm15M H m m STAES PATENT oFFi f ALBERT E. BLACKMAN, OF NEW YORK, N. Y.

METAL BOX-CORNER. FASTENER.

Application filed April 23, 1921. Serial No. 464,018. I

To all whom it may concern:

Be it known that I, ALBERT E. BLACKMAN, a citizen of the United States,residing at New York city, in the county of New York and State of NewYork, have invented certain new and useful Improvements in MetalBox-Corner Fasteners, of which the followin is a specification.

lVly invention relates toimprovements in metal box Construction and moreparticularly to boxes used to encase electrical switches or otherelectrical devices commonly known commercially as metal switch boxes.

The customary procedure when assembling or forming boxes of thischaracter is to bend the side and end walls to their upright positionand hold each corner with a pair of pliers or other suitable means untilthe spot-weld or rivet has been applied. The result of this mode offorming up boxes is very unsatisfactory, because it will be understoodthat heavy gauge metal is naturally springy and the tendency of thewalls when bent upright is to spring outward so that the operator isrequired to hold the.corners in place until the spot-weld has beenapplied. This task is not at all easy and the corners often slip out oftrue while being welded, which results in an uneven box.

The object of the present invention is to provide means whereby the sidewalls of a metal box, of the character hereinafter described, may besecurely attached together without the use of spot-welding or rivets.

A still further object of the invention is the provision of a box-blankof heavy gauge Fig. 3 is a perspective view of one cornerof the boxshowing the end wall before it is locked in upright position.

Fig. 4, is a plan view of the development or blank of one corner of thebox.

Referring to the drawing 10 denotes the body of a switch-box having asuitable cover 11, hinged on ears l2, projecting from one end of theupper portion of the body of the box 10. The side walls 13, and endwalls 14, are bent upright from the bottom 15. The edges of the endwalls are provided with extensions or ears 16, which are adapted to bebent at right angles to the end walls and are provided with suitablyshaped tongues 17. The free edge of each tongue is preferably raisedslightly beyond the plane of the remaining portion of the ear and liesparallel thereto, so that when the ear is brought into position thetongue 17, will be projected into the interior of the box. It will benoted with reference to the drawing that the arcuate cut in each of theears 16, forming a tongue 17, begins and ends at the bend forming thecorner of the. box, so that when the box is assembled the free edge ofthe tongues will be disposed toward the center of the side walls 13.

Adjacent the front and rear edges of the side walls 13, a pair ofoppositely extending tongues 18 and 19, are arranged, one being disposedabove the other. These tongues 18 and 19 respectively, are also bentbeyond and then parallel to the walls so. that when the side walls arein upright position the tongues will be projected into the interior ofthe box.

It will be apparent that should the upright walls of the box-form be ofsuch height that one group of interlocking tongues would not besufficient to securely hold the walls in their proper place, any adsidewalls 13 and end walls 14, are raised to a vertical position. The cars16 will ride in on the inner face of the side walls until the straightedges of the ears 16 abut the I closed end of the upper tongues 18 bnthe side walls 13, and at this point the lower tongues 19 w1ll haveentered the space left by the tongues 17 on the ears 16. The free edgesof the lower tongues 19 in the position just described, will be seatedagainst the edge of the cut left by the inwardly bent tongues 17 uponthe ears 16. It will be noted that when the sides of the box areinterlocked by means of the tongues 18 and 19, respectively, with theend wall 14, that it is practically impossible to move the latter wallseither inwardly or outwardly If it is further desired to more securelyattach the walls together at the corners a spot-weld may be applied, butin practice it has been found that the metal is of suflicient stifinessto assure the permanent locking of the walls and will withstand the mostsevere strains without becoming disengaged. The overlying portion of theupper tongues 18, upon the inner edge of the cars 16, provides a meanswhereby the side walls 13 are held in vertical position, thus thetongues 18 perform the dual function of preventing the inward movementof the end walls 14 and also the outward movement of the side walls 13.

not limited to interlocking the walls of the body of a metal box, butmay also be successfully employed in the cover of the box where for someparticular reason the lid or cover is of deep construction toaccommodate an electrical device having considerable height.

It has been found in practice that the coextending tongues 17 and 19 maybe omitted in the construction of the corners and cars 16 of the boxwhen a very heavy gauge metal is used and in their place I propose toset the ear 16 in its proper position by means of an offset caused bystriking the surface of the overlapped corner portion with a punch orother suitable means, whereby a dent or inset may be made in themembers. This construction is particularly advantageous where very heavygauge metal is used and it is a simple operation to inset, as shown at20 in Fig. 5, the adjacent surfaces of the metal ear 16 and wall 13.

The use of knock-out plugs 21 in the walls 13 and 1 of the body portionof the box 10 is known not to be new in the art, but their use inconnection with the specific form of box construction herein describedis of particular importance because these knock-out plugs may beindicated on the walls 13 and 14 by one operation of the cutting die andat the same time that the tab or tongue 19 is struck out.

1. A folded metal box formed from a cut blank, the body portionof saidblank provided with marginal portions adapted to be bent to form thesides of said box, corner ears bent at substantially right angles toeach of the edges of alternate side portions, each of said ears havingan opening therein, and

. openings therein, It will be understood that the invention is mamaspairs of oppositely extending tongues provided in the other alternateside portions and adapted to interlock with the edges of said ears, onemember of each of said pairs of tongues making surface engagement withbut not projecting beyond the plane of said ears, and the edges formedby said openings therein whereby each of the sides of said box may belocked in engagement with the adjacent side portion.

2. A folded metal box formed from a cut blank, the body portion of saidblank provided with ad acent marginal portions capable of being bent toform side wall members, additional side wall members provided with earsdisposed at right angles thereto and adapted to lie parallel to thefirst mentioned side wall members, an opening formed in the surface ofeach of said ears, and pairs of oppositely extending tongues provided inthe first mentioned side wall members adapted to engage the edges ofsaid ears and the edges formed by said one of said tongues of each pa1rmaking surface engagement with but not projecting beyond the plane ofsaid ears, whereby the wall members may be held against separation.

3. A folding box made from a cut blank having a bottom provided withmarginal portions adapted to be bent to form sides and ends of said box,said ends being provided with ears bent at substantially right anglesthereto and having a tongue struck up in each ear, said ears havingopposed edges formed by the ends of the ears and the edges formed bycutting out said tongues, and pairs of oppositely extending tonguesstruck up from the surface of the sides not having said ears, one memberof each of said last named tongues making surface engagement with butnot projecting beyond the plane of said ears, said last named tonguesbeing further disposed to limit the inward and outward movement of saidends.

4. A folding metal box made from a cut blank having marginal portionsadapted to be bent to form the walls of said box, the two alternatewalls having ears extendin at substantially right angles thereto anprovided with struck up tongues which form an opening and the outer'edgeof said ears, and pairs of oppositely arranged tongues struck up fromthe side walls not having the said ears, said last named tongues beingdisposed one above the other so that when the side walls having the earsare bent the last named tongues will engage the said opposed exposededges of the ears, one member of each of said pairs of tonguesprojecting to but not beyond and those of the openings formed by thetongues in the ears thereby interlocking the walls against relativemovement.

expose an edge opposite tothe plane of the adjacent cars 5. A foldedmetal box formed from a cut blank having marginal portions which arebent at substantially right angles to the portion forming the bottom ofsaid box, ears on two of the marginal bent portions adapted to extendsubstantially parallel to the adjacent marginal bent portions, each ofsaid ears having an opening therein which presents an edge which isopposite to the outer edge of said ear, and pairs of tongues struck upfrom the surface of each marginal portion not having said ears, the

free end of said tongues extending substan tially parallel thereto, saidtongues extending in opposite directions and arranged one above theother whereby when the marginal portions not having the ears are bentthe portions having the ears'may be moved in an arcuate course until thesaid outer edge of said ear moves under said upper tongue and seatsagainst the rear ofthe latter, one member of each pair of tonguesprojecting to but not beyond the plane of said ears when they interlock.

6. A metal box, comprising a bottom and side walls, ears projecting fromcertain of said side walls and lying parallel to the other side walls,and pairs of oppositely pro- .jecting tongues in one side wall engagingan adjacent ear in another side wall, one member of each of said pairsof tongues making surface engagement with but not projecting beyond theplane of said ears.

7. A metal box, comprising a bottom and side walls, a pair of oppositelyprojecting tongues struck up near the two ends of each of two of saidside walls, ears carried at make surface engagement with but not projectbeyond the plane of said ear In testimony whereof I have aed mysignature.

ALBERT n. shalom,

